In flamenco guitar, picado is the act of playing melodic passages using mainly the index and middle fingers in an alternating fashion. In classical guitar terminology picado is known as "rest stroke" where the finger, after striking the string to make the sound, rests on the next upper string. Two key values attached to picado are tone and speed. To generate a full tone that projects well, the finger has to first push on the string toward the soundboard and then release it to make the note. The ideal spot for a good picado tone is the left corner of the right hand fingertip where the nail meets the flesh.

As for speed, primarily it is important to be economical in terms of finger movement. Picado has to be played with as little motion as possible. A good way to practise picado for speed is to play each note staccato, muting the string with the next finger right after the first one strikes.

It is quite difficult to achieve speed by practising scales while incrementally raising the tempo on the metronome. No matter how long and persistently you practise your scales with the metronome, slowly going faster and faster, you will plateau at some point on the speed scale. Speed is not a natural outcome of hours you put into your practice. If that were the case, all the classical players who do 5-6 hours of practice per day would be playing scales at lightning speed. But we all know that's not the case. The player has to aim for speed via a different mind set and practice routine. The operative term here is "speed burst." Try to play multiple notes one after the other like a "twitch" regarding them as one beat. Watch the following video to see what I mean:

Once you gain access to that twitch muscle that gives you the speed burst you need,​then you conceptualize the scales as a combination of speed bursts.

:One last thing, it is not possible to play picado by only moving the tips of your fingers. That is a misconception driven by the belief that Paco de Lucia does it that way. The main force of picado always comes from the knuckle, that is the main joint. The reason Paco seems to be moving only the first two joints is because he does the movements very economically.